WASHINGTON DC — On June 5, Saudi Arabia and its allies, including Egypt, the United Arab Emirates and Bahrain, cut diplomatic ties with Qatar, accusing it of funding extremist groups such as the Muslim Brotherhood and Islamic State.

In response, Qatar said it was the victim of a policy of “domination and control” by its larger neighbor and that Saudi Arabia was, in fact, the one responsible for backing extremism.

So what is the truth? Fundamentalist strains of Islam, including Saudi-born Salafism and Wahhabism, form the ideological bedrock for most terror groups. According to a study by Leif Wenar of King’s College London based on the Global Terrorism Database, three out of four terror attacks in the last 10 years have been conducted by people espousing Salafist ideology.

Wenar said Saudi Arabia is the chief exporter of Salafism around the world, spending tens of billions of dollars to build mosques, fund madrassas, finance preachers and offer scholarships to students to study the rigid form of Islam.

The effort is possibly the most expensive ideological campaign in human history, Wenar told VOA.

“Saudi Arabia is not the only factor, of course, in the spread of violent extremism. But for 50 years Saudi Arabia has been funding schools and mosques and radical preachers worldwide who have set down their particular narrow and puritanical version of Islam, which has in many places mutated into the violent extremism we see today,” Wenar said.